package edu.nuc.ahm.juc.readwrite;

import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/*
*
* 独占锁（写锁） 一次只能被一个线程占有
* 共享锁（读锁）多个线程可以同时占有
*
*
* 写入 原子性 操作
* ReadWriteLock
* 读---读    可以共存
* 读---写    不能共存
* 写---写    不能共存
*
*
* */
public class ReadWriteLockDemo {
    public static void main(String[] args) {
        Mychache2 mychache = new Mychache2();
        for (int i = 1; i <=5; i++) {
            final int temp = i;
            new Thread(()->{
                mychache.put(""+temp,""+temp);
            },String.valueOf(i)).start();
        }

        for (int i = 1; i <= 5; i++) {
            final int temp = i;
            new Thread(()->{
                mychache.get(temp+"");
            },String.valueOf(i)).start();
        }
    }
}

/**
 * 自定义缓存
 */
class Mychache{
    private volatile Map<String,Object> map = new HashMap<>();

    // 存， 写
    public void put(String key,Object value){
        System.out.println(Thread.currentThread().getName()+"写入"+key);
        map.put(key,value);
        System.out.println(Thread.currentThread().getName()+"写入OK");
    }

    // 取 读
    public void get(String key){
        System.out.println(Thread.currentThread().getName()+"读取"+key);
        Object o = map.get(key);
        System.out.println(Thread.currentThread().getName()+"读取OK");
    }
}

/**
 * 自定义缓存
 */
class Mychache2{
    private volatile Map<String,Object> map = new HashMap<>();
    // 更加细粒度的操作
    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();


    // 存 写入的时候 只希望同时只有一个线程写



    // 存， 写
    public void put(String key,Object value){
        readWriteLock.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"写入"+key);
            map.put(key,value);
            System.out.println(Thread.currentThread().getName()+"写入OK");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            readWriteLock.writeLock().unlock();
        }

    }

    // 取 读
    public void get(String key){

//        readWriteLock.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"读取"+key);
            Object o = map.get(key);
            System.out.println(Thread.currentThread().getName()+"读取OK");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
//            readWriteLock.readLock().unlock();
        }

    }


}

